Portis, 29, started all five games he played in an injury-riddled 2010, finishing with 227 rushing yards on 54 carries and two rushing touchdowns.

"Clinton provided excitement from the very first time he touched the ball as a Redskin and we were lucky to witness every ounce of energy, effort and passion he has given ever since," Redskins owner Daniel Snyder said in a statement.

"He will always be a Redskin and go down as one of the franchise's all-time greats."

In seven years in Washington, Portis rushed for 6,824 yards and 46 touchdowns, trailing only John Riggins (7,472) on the Redskins' rushing list.

"Being a Redskin was a special part of my life," he said. "Coming and being in that organization, I turned from a kid having fun to a man carrying responsibilities.

"I tried to put the world on my shoulders for (former) coach (Joe) Gibbs and the Redskins fans."